A survey of United States dairy cattle nutritionists' practices and perceptions of reducing crude protein in lactating dairy cow diets

Objective: The objective was to assess if US dairy nutritionists' approaches toward balancing CP in lactating cow diets are influenced by demographic information, feelings toward environmental nitrogen (N) excretion, and dietary CP cost. Materials and Methods: An electronic survey was sent to 886 US certified dairy nutritionists through the database of the American Registry of Professional Animal Scientists (ARPAS) via email. For survey data analysis, a nonparametric statistic was used to check whether the responses to each question were independent. Relationships among demographic data and responses to other questions were performed using Spearman's correlation. Poisson regression and least squares means were used to identify statistically meaningful differences between response counts within each respective question. Results and Discussion: A total of 77 nutritionists representing 1,065 herds from 28 states with a total of 521,000 total lactating dairy cows responded to the questionnaire. Eighty-nine percent of nutritionists balanced diets based on one or more individual AA requirements of dairy cows. Most respondents (72%) reported that they are currently formulating diets with lower dietary CP than they were 3 to 5 yr ago. The primary concern with formulating lower CP diets was the cost per unit of MP, likely due to the high and fluctuating cost of high-RUP feedstuffs. Implications and Applications: Currently, the impetus to reduce dietary CP in lactating cow diets is primarily financially, rather than environmentally, driven. Nutrition models that accurately predict individual AA requirements of dairy cows will allow nutritionists to develop even lower CP diets than is presently possible. Monitoring income over feed cost of low-CP diets supplemented with AA is critical to support the sustainability of the dairy industry.